/*
 * The little filesystem
 *
 * Copyright (c) 2017, Arm Limited. All rights reserved.
 * SPDX-License-Identifier: BSD-3-Clause
 */
#ifndef LFS_H
#define LFS_H

#include <stdbool.h>
#include <stdint.h>


#ifdef __cplusplus
extern "C" {
#endif


/// Version info ///

// Software library version
// Major (top-nibble), incremented on backwards incompatible changes
// Minor (bottom-nibble), incremented on feature additions
#define LFS_VERSION 0x00020002
#define LFS_VERSION_MAJOR (0xffff & (LFS_VERSION >> 16))
#define LFS_VERSION_MINOR (0xffff & (LFS_VERSION >> 0))

// Version of On-disk data structures
// Major (top-nibble), incremented on backwards incompatible changes
// Minor (bottom-nibble), incremented on feature additions
#define LFS_DISK_VERSION 0x00020000
#define LFS_DISK_VERSION_MAJOR (0xffff & (LFS_DISK_VERSION >> 16))
#define LFS_DISK_VERSION_MINOR (0xffff & (LFS_DISK_VERSION >> 0))


/// Definitions ///

// Type definitions
typedef uint32_t lfs_size_t;
typedef uint32_t lfs_off_t;

typedef int32_t lfs_ssize_t;
typedef int32_t lfs_soff_t;

typedef uint32_t lfs_block_t;

// Maximum name size in bytes, may be redefined to reduce the size of the
// info struct. Limited to <= 1022. Stored in superblock and must be
// respected by other littlefs drivers.
#ifndef LFS_NAME_MAX
#define LFS_NAME_MAX 255
#endif

// Maximum size of a file in bytes, may be redefined to limit to support other
// drivers. Limited on disk to <= 4294967296. However, above 2147483647 the
// functions lfs_file_seek, lfs_file_size, and lfs_file_tell will return
// incorrect values due to using signed integers. Stored in superblock and
// must be respected by other littlefs drivers.
#ifndef LFS_FILE_MAX
#define LFS_FILE_MAX 2147483647
#endif

// Maximum size of custom attributes in bytes, may be redefined, but there is
// no real benefit to using a smaller LFS_ATTR_MAX. Limited to <= 1022.
#ifndef LFS_ATTR_MAX
#define LFS_ATTR_MAX 1022
#endif

// Possible error codes, these are negative to allow
// valid positive return values
enum lfs_error
{
	LFS_ERR_OK = 0,				// No error
	LFS_ERR_IO = -5,			// Error during device operation
	LFS_ERR_CORRUPT = -84,		// Corrupted
	LFS_ERR_NOENT = -2,			// No directory entry
	LFS_ERR_EXIST = -17,		// Entry already exists
	LFS_ERR_NOTDIR = -20,		// Entry is not a dir
	LFS_ERR_ISDIR = -21,		// Entry is a dir
	LFS_ERR_NOTEMPTY = -39,		// Dir is not empty
	LFS_ERR_BADF = -9,			// Bad file number
	LFS_ERR_FBIG = -27,			// File too large
	LFS_ERR_INVAL = -22,		// Invalid parameter
	LFS_ERR_NOSPC = -28,		// No space left on device
	LFS_ERR_NOMEM = -12,		// No more memory available
	LFS_ERR_NOATTR = -61,		// No data/attr available
	LFS_ERR_NAMETOOLONG = -36,	// File name too long
};

// File types
enum lfs_type
{
	// file types
	LFS_TYPE_REG = 0x001,
	LFS_TYPE_DIR = 0x002,

	// internally used types
	LFS_TYPE_SPLICE = 0x400,
	LFS_TYPE_NAME = 0x000,
	LFS_TYPE_STRUCT = 0x200,
	LFS_TYPE_USERATTR = 0x300,
	LFS_TYPE_FROM = 0x100,
	LFS_TYPE_TAIL = 0x600,
	LFS_TYPE_GLOBALS = 0x700,
	LFS_TYPE_CRC = 0x500,

	// internally used type specializations
	LFS_TYPE_CREATE = 0x401,
	LFS_TYPE_DELETE = 0x4ff,
	LFS_TYPE_SUPERBLOCK = 0x0ff,
	LFS_TYPE_DIRSTRUCT = 0x200,
	LFS_TYPE_CTZSTRUCT = 0x202,
	LFS_TYPE_INLINESTRUCT = 0x201,
	LFS_TYPE_SOFTTAIL = 0x600,
	LFS_TYPE_HARDTAIL = 0x601,
	LFS_TYPE_MOVESTATE = 0x7ff,

	// internal chip sources
	LFS_FROM_NOOP = 0x000,
	LFS_FROM_MOVE = 0x101,
	LFS_FROM_USERATTRS = 0x102,
};

// File open flags
enum lfs_open_flags
{
	// open flags
	LFS_O_RDONLY = 1,		// Open a file as read only
	LFS_O_WRONLY = 2,		// Open a file as write only
	LFS_O_RDWR = 3,			// Open a file as read and write
	LFS_O_CREAT = 0x0100,	// Create a file if it does not exist
	LFS_O_EXCL = 0x0200,	// Fail if a file already exists
	LFS_O_TRUNC = 0x0400,	// Truncate the existing file to zero size
	LFS_O_APPEND = 0x0800,	// Move to end of file on every write

	// internally used flags
	LFS_F_DIRTY = 0x010000,	   // File does not match storage
	LFS_F_WRITING = 0x020000,  // File has been written since last flush
	LFS_F_READING = 0x040000,  // File has been read since last flush
	LFS_F_ERRED = 0x080000,	   // An error occured during write
	LFS_F_INLINE = 0x100000,   // Currently inlined in directory entry
	LFS_F_OPENED = 0x200000,   // File has been opened
};

// File seek flags
enum lfs_whence_flags
{
	LFS_SEEK_SET = 0,  // Seek relative to an absolute position
	LFS_SEEK_CUR = 1,  // Seek relative to the current file position
	LFS_SEEK_END = 2,  // Seek relative to the end of the file
};


// Configuration provided during initialization of the littlefs
struct lfs_config
{
	// Opaque user provided context that can be used to pass
	// information to the block device operations
	void *context;

	// Read a region in a block. Negative error codes are propogated
	// to the user.
	int (*read)(const struct lfs_config *c, lfs_block_t block, lfs_off_t off, void *buffer, lfs_size_t size);

	// Program a region in a block. The block must have previously
	// been erased. Negative error codes are propogated to the user.
	// May return LFS_ERR_CORRUPT if the block should be considered bad.
	int (*prog)(const struct lfs_config *c, lfs_block_t block, lfs_off_t off, const void *buffer, lfs_size_t size);

	// Erase a block. A block must be erased before being programmed.
	// The state of an erased block is undefined. Negative error codes
	// are propogated to the user.
	// May return LFS_ERR_CORRUPT if the block should be considered bad.
	int (*erase)(const struct lfs_config *c, lfs_block_t block);

	// Sync the state of the underlying block device. Negative error codes
	// are propogated to the user.
	int (*sync)(const struct lfs_config *c);

	// Minimum size of a block read. All read operations will be a
	// multiple of this value.
	lfs_size_t read_size;

	// Minimum size of a block program. All program operations will be a
	// multiple of this value.
	lfs_size_t prog_size;

	// Size of an erasable block. This does not impact ram consumption and
	// may be larger than the physical erase size. However, non-inlined files
	// take up at minimum one block. Must be a multiple of the read
	// and program sizes.
	lfs_size_t block_size;

	// Number of erasable blocks on the device.
	lfs_size_t block_count;

	// Number of erase cycles before littlefs evicts metadata logs and moves
	// the metadata to another block. Suggested values are in the
	// range 100-1000, with large values having better performance at the cost
	// of less consistent wear distribution.
	//
	// Set to -1 to disable block-level wear-leveling.
	int32_t block_cycles;

	// Size of block caches. Each cache buffers a portion of a block in RAM.
	// The littlefs needs a read cache, a program cache, and one additional
	// cache per file. Larger caches can improve performance by storing more
	// data and reducing the number of disk accesses. Must be a multiple of
	// the read and program sizes, and a factor of the block size.
	lfs_size_t cache_size;

	// Size of the lookahead buffer in bytes. A larger lookahead buffer
	// increases the number of blocks found during an allocation pass. The
	// lookahead buffer is stored as a compact bitmap, so each byte of RAM
	// can track 8 blocks. Must be a multiple of 8.
	lfs_size_t lookahead_size;

	// Optional statically allocated read buffer. Must be cache_size.
	// By default lfs_malloc is used to allocate this buffer.
	void *read_buffer;

	// Optional statically allocated program buffer. Must be cache_size.
	// By default lfs_malloc is used to allocate this buffer.
	void *prog_buffer;

	// Optional statically allocated lookahead buffer. Must be lookahead_size
	// and aligned to a 32-bit boundary. By default lfs_malloc is used to
	// allocate this buffer.
	void *lookahead_buffer;

	// Optional upper limit on length of file names in bytes. No downside for
	// larger names except the size of the info struct which is controlled by
	// the LFS_NAME_MAX define. Defaults to LFS_NAME_MAX when zero. Stored in
	// superblock and must be respected by other littlefs drivers.
	lfs_size_t name_max;

	// Optional upper limit on files in bytes. No downside for larger files
	// but must be <= LFS_FILE_MAX. Defaults to LFS_FILE_MAX when zero. Stored
	// in superblock and must be respected by other littlefs drivers.
	lfs_size_t file_max;

	// Optional upper limit on custom attributes in bytes. No downside for
	// larger attributes size but must be <= LFS_ATTR_MAX. Defaults to
	// LFS_ATTR_MAX when zero.
	lfs_size_t attr_max;
};

// File info structure
struct lfs_info
{
	// Type of the file, either LFS_TYPE_REG or LFS_TYPE_DIR
	uint8_t type;

	// Size of the file, only valid for REG files. Limited to 32-bits.
	lfs_size_t size;

	// Name of the file stored as a null-terminated string. Limited to
	// LFS_NAME_MAX+1, which can be changed by redefining LFS_NAME_MAX to
	// reduce RAM. LFS_NAME_MAX is stored in superblock and must be
	// respected by other littlefs drivers.
	char name[LFS_NAME_MAX + 1];
};

// Custom attribute structure, used to describe custom attributes
// committed atomically during file writes.
struct lfs_attr
{
	// 8-bit type of attribute, provided by user and used to
	// identify the attribute
	uint8_t type;

	// Pointer to buffer containing the attribute
	void *buffer;

	// Size of attribute in bytes, limited to LFS_ATTR_MAX
	lfs_size_t size;
};

// Optional configuration provided during lfs_file_opencfg
struct lfs_file_config
{
	// Optional statically allocated file buffer. Must be cache_size.
	// By default lfs_malloc is used to allocate this buffer.
	void *buffer;

	// Optional list of custom attributes related to the file. If the file
	// is opened with read access, these attributes will be read from disk
	// during the open call. If the file is opened with write access, the
	// attributes will be written to disk every file sync or close. This
	// write occurs atomically with update to the file's contents.
	//
	// Custom attributes are uniquely identified by an 8-bit type and limited
	// to LFS_ATTR_MAX bytes. When read, if the stored attribute is smaller
	// than the buffer, it will be padded with zeros. If the stored attribute
	// is larger, then it will be silently truncated. If the attribute is not
	// found, it will be created implicitly.
	struct lfs_attr *attrs;

	// Number of custom attributes in the list
	lfs_size_t attr_count;
};


/// internal littlefs data structures ///
typedef struct lfs_cache
{
	lfs_block_t block;
	lfs_off_t off;
	lfs_size_t size;
	uint8_t *buffer;
} lfs_cache_t;

typedef struct lfs_mdir
{
	lfs_block_t pair[2];
	uint32_t rev;
	lfs_off_t off;
	uint32_t etag;
	uint16_t count;
	bool erased;
	bool split;
	lfs_block_t tail[2];
} lfs_mdir_t;

// littlefs directory type
typedef struct lfs_dir
{
	struct lfs_dir *next;
	uint16_t id;
	uint8_t type;
	lfs_mdir_t m;

	lfs_off_t pos;
	lfs_block_t head[2];
} lfs_dir_t;

// littlefs file type
typedef struct lfs_file
{
	struct lfs_file *next;
	uint16_t id;
	uint8_t type;
	lfs_mdir_t m;

	struct lfs_ctz
	{
		lfs_block_t head;
		lfs_size_t size;
	} ctz;

	uint32_t flags;
	lfs_off_t pos;
	lfs_block_t block;
	lfs_off_t off;
	lfs_cache_t cache;

	const struct lfs_file_config *cfg;
} lfs_file_t;

typedef struct lfs_superblock
{
	uint32_t version;
	lfs_size_t block_size;
	lfs_size_t block_count;
	lfs_size_t name_max;
	lfs_size_t file_max;
	lfs_size_t attr_max;
} lfs_superblock_t;

typedef struct lfs_gstate
{
	uint32_t tag;
	lfs_block_t pair[2];
} lfs_gstate_t;

// The littlefs filesystem type
typedef struct lfs
{
	lfs_cache_t rcache;
	lfs_cache_t pcache;

	lfs_block_t root[2];
	struct lfs_mlist
	{
		struct lfs_mlist *next;
		uint16_t id;
		uint8_t type;
		lfs_mdir_t m;
	} * mlist;
	uint32_t seed;

	lfs_gstate_t gstate;
	lfs_gstate_t gdisk;
	lfs_gstate_t gdelta;

	struct lfs_free
	{
		lfs_block_t off;
		lfs_block_t size;
		lfs_block_t i;
		lfs_block_t ack;
		uint32_t *buffer;
	} free;

	const struct lfs_config *cfg;
	lfs_size_t name_max;
	lfs_size_t file_max;
	lfs_size_t attr_max;

#ifdef LFS_MIGRATE
	struct lfs1 *lfs1;
#endif
} lfs_t;


/// Filesystem functions ///

// Format a block device with the littlefs
//
// Requires a littlefs object and config struct. This clobbers the littlefs
// object, and does not leave the filesystem mounted. The config struct must
// be zeroed for defaults and backwards compatibility.
//
// Returns a negative error code on failure.
int lfs_format(lfs_t *lfs, const struct lfs_config *config);

// Mounts a littlefs
//
// Requires a littlefs object and config struct. Multiple filesystems
// may be mounted simultaneously with multiple littlefs objects. Both
// lfs and config must be allocated while mounted. The config struct must
// be zeroed for defaults and backwards compatibility.
//
// Returns a negative error code on failure.
int lfs_mount(lfs_t *lfs, const struct lfs_config *config);

// Unmounts a littlefs
//
// Does nothing besides releasing any allocated resources.
// Returns a negative error code on failure.
int lfs_unmount(lfs_t *lfs);

/// General operations ///

// Removes a file or directory
//
// If removing a directory, the directory must be empty.
// Returns a negative error code on failure.
int lfs_remove(lfs_t *lfs, const char *path);

// Rename or move a file or directory
//
// If the destination exists, it must match the source in type.
// If the destination is a directory, the directory must be empty.
//
// Returns a negative error code on failure.
int lfs_rename(lfs_t *lfs, const char *oldpath, const char *newpath);

// Find info about a file or directory
//
// Fills out the info structure, based on the specified file or directory.
// Returns a negative error code on failure.
int lfs_stat(lfs_t *lfs, const char *path, struct lfs_info *info);

// Get a custom attribute
//
// Custom attributes are uniquely identified by an 8-bit type and limited
// to LFS_ATTR_MAX bytes. When read, if the stored attribute is smaller than
// the buffer, it will be padded with zeros. If the stored attribute is larger,
// then it will be silently truncated. If no attribute is found, the error
// LFS_ERR_NOATTR is returned and the buffer is filled with zeros.
//
// Returns the size of the attribute, or a negative error code on failure.
// Note, the returned size is the size of the attribute on disk, irrespective
// of the size of the buffer. This can be used to dynamically allocate a buffer
// or check for existance.
lfs_ssize_t lfs_getattr(lfs_t *lfs, const char *path, uint8_t type, void *buffer, lfs_size_t size);

// Set custom attributes
//
// Custom attributes are uniquely identified by an 8-bit type and limited
// to LFS_ATTR_MAX bytes. If an attribute is not found, it will be
// implicitly created.
//
// Returns a negative error code on failure.
int lfs_setattr(lfs_t *lfs, const char *path, uint8_t type, const void *buffer, lfs_size_t size);

// Removes a custom attribute
//
// If an attribute is not found, nothing happens.
//
// Returns a negative error code on failure.
int lfs_removeattr(lfs_t *lfs, const char *path, uint8_t type);


/// File operations ///

// Open a file
//
// The mode that the file is opened in is determined by the flags, which
// are values from the enum lfs_open_flags that are bitwise-ored together.
//
// Returns a negative error code on failure.
int lfs_file_open(lfs_t *lfs, lfs_file_t *file, const char *path, int flags);

// Open a file with extra configuration
//
// The mode that the file is opened in is determined by the flags, which
// are values from the enum lfs_open_flags that are bitwise-ored together.
//
// The config struct provides additional config options per file as described
// above. The config struct must be allocated while the file is open, and the
// config struct must be zeroed for defaults and backwards compatibility.
//
// Returns a negative error code on failure.
int lfs_file_opencfg(lfs_t *lfs, lfs_file_t *file, const char *path, int flags, const struct lfs_file_config *config);

// Close a file
//
// Any pending writes are written out to storage as though
// sync had been called and releases any allocated resources.
//
// Returns a negative error code on failure.
int lfs_file_close(lfs_t *lfs, lfs_file_t *file);

// Synchronize a file on storage
//
// Any pending writes are written out to storage.
// Returns a negative error code on failure.
int lfs_file_sync(lfs_t *lfs, lfs_file_t *file);

// Read data from file
//
// Takes a buffer and size indicating where to store the read data.
// Returns the number of bytes read, or a negative error code on failure.
lfs_ssize_t lfs_file_read(lfs_t *lfs, lfs_file_t *file, void *buffer, lfs_size_t size);

// Write data to file
//
// Takes a buffer and size indicating the data to write. The file will not
// actually be updated on the storage until either sync or close is called.
//
// Returns the number of bytes written, or a negative error code on failure.
lfs_ssize_t lfs_file_write(lfs_t *lfs, lfs_file_t *file, const void *buffer, lfs_size_t size);

// Change the position of the file
//
// The change in position is determined by the offset and whence flag.
// Returns the new position of the file, or a negative error code on failure.
lfs_soff_t lfs_file_seek(lfs_t *lfs, lfs_file_t *file, lfs_soff_t off, int whence);

// Truncates the size of the file to the specified size
//
// Returns a negative error code on failure.
int lfs_file_truncate(lfs_t *lfs, lfs_file_t *file, lfs_off_t size);

// Return the position of the file
//
// Equivalent to lfs_file_seek(lfs, file, 0, LFS_SEEK_CUR)
// Returns the position of the file, or a negative error code on failure.
lfs_soff_t lfs_file_tell(lfs_t *lfs, lfs_file_t *file);

// Change the position of the file to the beginning of the file
//
// Equivalent to lfs_file_seek(lfs, file, 0, LFS_SEEK_SET)
// Returns a negative error code on failure.
int lfs_file_rewind(lfs_t *lfs, lfs_file_t *file);

// Return the size of the file
//
// Similar to lfs_file_seek(lfs, file, 0, LFS_SEEK_END)
// Returns the size of the file, or a negative error code on failure.
lfs_soff_t lfs_file_size(lfs_t *lfs, lfs_file_t *file);


/// Directory operations ///

// Create a directory
//
// Returns a negative error code on failure.
int lfs_mkdir(lfs_t *lfs, const char *path);

// Open a directory
//
// Once open a directory can be used with read to iterate over files.
// Returns a negative error code on failure.
int lfs_dir_open(lfs_t *lfs, lfs_dir_t *dir, const char *path);

// Close a directory
//
// Releases any allocated resources.
// Returns a negative error code on failure.
int lfs_dir_close(lfs_t *lfs, lfs_dir_t *dir);

// Read an entry in the directory
//
// Fills out the info structure, based on the specified file or directory.
// Returns a positive value on success, 0 at the end of directory,
// or a negative error code on failure.
int lfs_dir_read(lfs_t *lfs, lfs_dir_t *dir, struct lfs_info *info);

// Change the position of the directory
//
// The new off must be a value previous returned from tell and specifies
// an absolute offset in the directory seek.
//
// Returns a negative error code on failure.
int lfs_dir_seek(lfs_t *lfs, lfs_dir_t *dir, lfs_off_t off);

// Return the position of the directory
//
// The returned offset is only meant to be consumed by seek and may not make
// sense, but does indicate the current position in the directory iteration.
//
// Returns the position of the directory, or a negative error code on failure.
lfs_soff_t lfs_dir_tell(lfs_t *lfs, lfs_dir_t *dir);

// Change the position of the directory to the beginning of the directory
//
// Returns a negative error code on failure.
int lfs_dir_rewind(lfs_t *lfs, lfs_dir_t *dir);


/// Filesystem-level filesystem operations

// Finds the current size of the filesystem
//
// Note: Result is best effort. If files share COW structures, the returned
// size may be larger than the filesystem actually is.
//
// Returns the number of allocated blocks, or a negative error code on failure.
lfs_ssize_t lfs_fs_size(lfs_t *lfs);

// Traverse through all blocks in use by the filesystem
//
// The provided callback will be called with each block address that is
// currently in use by the filesystem. This can be used to determine which
// blocks are in use or how much of the storage is available.
//
// Returns a negative error code on failure.
int lfs_fs_traverse(lfs_t *lfs, int (*cb)(void *, lfs_block_t), void *data);

#ifdef LFS_MIGRATE
// Attempts to migrate a previous version of littlefs
//
// Behaves similarly to the lfs_format function. Attempts to mount
// the previous version of littlefs and update the filesystem so it can be
// mounted with the current version of littlefs.
//
// Requires a littlefs object and config struct. This clobbers the littlefs
// object, and does not leave the filesystem mounted. The config struct must
// be zeroed for defaults and backwards compatibility.
//
// Returns a negative error code on failure.
int lfs_migrate(lfs_t *lfs, const struct lfs_config *cfg);
#endif


#ifdef __cplusplus
} /* extern "C" */
#endif

#endif
